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Monday, May 23

  1. page space.menu edited ... Nucleophilic Substitution Reactions The Haber Process Acids and Bases
    ...
    Nucleophilic Substitution Reactions
    The Haber Process
    Acids and Bases
    (view changes)
    9:16 pm

Sunday, May 22

  1. page Acids and Bases edited ... NaCl In this example, the carbonic acid (H2CO3) formed undergoes rapid decomposition into wat…
    ...
    NaCl
    In this example, the carbonic acid (H2CO3) formed undergoes rapid decomposition into water and gaseous carbon dioxide (CO3 + H2 -> CO2 + H2O), and CO2 gas is released.
    Ka and Kb Constants
    Ka is a constant that has specific values for different acids. It is the measurement that gives values that indicates the strength of certain acids, for a strong acid, it ionizes completely in water. The stronger the acid, the higher the Ka values.
    A “strong” acid is an acid that completely ionizes.
    E.g. HCl + H2O → H3O + Cl
    A “weak” acid is an acid that doesn’t ionize completely.
    E.g. HF + H2O ↔ H3O + F
    Example, HA(aq) + H2O(l) ↔ H3O(aq) + A–(aq)
    Ka = [H3O+][A–] / [HA]
    Kb is a constant similar to Ka, Kb is a value for bases. The higher the value of Kb, the strong the base.
    Kb is similar to Ka except b stands for base
    The general reaction involving a base can be
    written as B(aq) + H2O ↔ BH(aq) + OH–(aq)
    Thus Kb = [BH+] [OH–] / [B]

    Kw and pH Constants
    Pure water ionizes very slightly, H2O(l) -> H+(aq) + OH-(aq), this self-ionization of water is an endothermic process. It can be explained using the le Chatlier's principle. The ionization equilibrium is affected by the temperature, if temperature is increased, the rate of ionization of water increases.
    ...
    pKw and pOH Constants
    Defining pOH
    ...
    in pOH.
    pOH

    pOH
    similar to
    ...
    calculated by:
    pOH

    pOH
    = -log [OH-(aq)]
    *Adding the values of pH and pOH together always yeild a product of 14. For example, if the pH of a solution is 2, the pOH of the solution is 12. Therefore, pH values of 7 is neutral, because pH is 7, pOH must be 14-7=7.

    Defining pKw
    pKw is the sum of the values of pH and pOH of a solution.
    pkw can be calculated by: pKw = pH + pOH = 14
    *Adding the values of pH and pOH together always yeild a product of 14. For example, if the pH of a solution is 2, the pOH of the solution is 12. Therefore, pH values of 7 is neutral, because pH is 7, pOH must be 14-7=7.

    (view changes)
    9:32 pm
  2. page Acids and Bases edited ... In this example, the carbonic acid (H2CO3) formed undergoes rapid decomposition into water and…
    ...
    In this example, the carbonic acid (H2CO3) formed undergoes rapid decomposition into water and gaseous carbon dioxide (CO3 + H2 -> CO2 + H2O), and CO2 gas is released.
    Kw and pH Constants
    ...
    water increases.
    Defining Kw
    Kw is the ionic product of water.
    ...
    Kw is always constant at a constant temperature regardless of the value of pH.
    Defining pH
    ...
    ion concentration.
    pH

    pH
    is logarithmic,
    ...
    calculated by:
    pH = -log[H+(aq)]
    The pH scale
    {ph_scale.JPG}
    pKw and pOH Constants
    Defining pOH
    Certain concentration of hydrogen and hydroxide ions has to be present in a solution for it to be acidic or basic. Similar to pH, pOH is the measurement of concentration of OH- ions in a solution. Because all solutions considered acidic or basic contains these ions, the alkalinity of the solution can be measured in pOH.
    pOH similar to the pH, is logarithmic, a 1 unit increase in the scale means a change in the factor of 10 in the concentration of OH- ions in the solution, pOH is calculated by:
    pOH = -log [OH-(aq)]
    *Adding the values of pH and pOH together always yeild a product of 14. For example, if the pH of a solution is 2, the pOH of the solution is 12. Therefore, pH values of 7 is neutral, because pH is 7, pOH must be 14-7=7.
    Defining pKw

    (view changes)
    9:14 pm
  3. page Acids and Bases edited ... NaCl In this example, the carbonic acid (H2CO3) formed undergoes rapid decomposition into wat…
    ...
    NaCl
    In this example, the carbonic acid (H2CO3) formed undergoes rapid decomposition into water and gaseous carbon dioxide (CO3 + H2 -> CO2 + H2O), and CO2 gas is released.
    Kw and pH Constants
    Pure water ionizes very slightly, H2O(l) -> H+(aq) + OH-(aq), this self-ionization of water is an endothermic process. It can be explained using the le Chatlier's principle. The ionization equilibrium is affected by the temperature, if temperature is increased, the rate of ionization of water increases.
    Defining Kw
    Kw is the ionic product of water.
    Kw = [H+(aq)] [OH-(aq)]
    At 25 degrees Celsius, Kw is equal to 1.0 x 10^-14 mol/L.
    Kw is always constant at a constant temperature regardless of the value of pH.
    Defining pH
    pH is the abbreviation for partial Hydrogen. Defining pH under the Bronsted-Lowry definition, the pH of the acids and bases are related to the concentration of hydrogen ions present. Acids increase the concentration of hydrogen ions, while bases decreases the concentration of hydrogen ions. The acidity of a solution can be measured from its hydrogen ion concentration.
    pH is logarithmic, meaning that 1 unit change in pH is a change factor of 10 in the concentration of proton ions, pH is calculated by:
    pH = -log[H+(aq)]
    The pH scale
    {ph_scale.JPG}

    (view changes)
    9:04 pm
  4. file ph_scale.JPG uploaded
    9:03 pm
  5. file ph scale.bmp uploaded
    9:02 pm
  6. page Acids and Bases edited ... In the late 18th century, Svante Arrhenius, a Swedish scientist proposed that water can dissol…
    ...
    In the late 18th century, Svante Arrhenius, a Swedish scientist proposed that water can dissolve many compounds by separating them into their individual ions. Arrhenius proposed that acids are compounds containing hydrogen that dissolves in water and donates one or more hydrogen ions (H+) into the solution. Acids are known as proton donors.
    An example of the dissociation of hydrochloric acid (HCl) in water:
    || HCl
    H2O
    {http://www.visionlearning.com/library/modules/mid58/Image/VLObject-488-021202021211.gif} arrow
    HCl(g) -> H+(aq)
    +
    Cl-(aq)
    + Cl-(aq)
    Arrhenius proposed that bases are substances that dissolves in water and release hydroxide ions (OH-) into the solution. Bases are also known as proton acceptors.
    ...
    in water:
    || NaOH
    H2O
    {http://www.visionlearning.com/library/modules/mid58/Image/VLObject-488-021202021211.gif} arrow

    NaOH ->
    Na+(aq)
    +
    OH-(aq)
    + OH-(aq)
    The Arrhenius
    ...
    called neutralization.
    Neutralization
    Acid and Base Neutralization
    ...
    or water.
    || H+(aq)

    H+(aq) + OH-(aq) -> H2O
    Neutralization of acid and base will always produce water and salt, shown below:
    *A salt is any ionic compound that contains any combination between the alkaline metals and halogens.
    Acids

    +
    OH-(aq)Bases
    {http://www.visionlearning.com/library/modules/mid58/Image/VLObject-488-021202021211.gif} arrow H2O
    Neutralization of acid and base will always produce water and salt, shown below:
    *A salt is any ionic compound that contains any combination between the alkaline metals and halogens.
    || Acid
    Base

    Water
    +
    Salt
    HCl
    +
    NaOH
    {http://www.visionlearning.com/library/modules/mid58/Image/VLObject-488-021202021211.gif} arrow H2O
    H2O

    +
    NaCl
    ...
    +
    KOH
    {http://www.visionlearning.com/library/modules/mid58/Image/VLObject-488-021202021211.gif} arrow H2O
    H2O

    +
    KBr
    ...
    is any sebstancesubstance that can
    ...
    a proton.
    For example, NaHCO3 or baking soda acts like a base by accepting a proton from an acid.
    || AcidAcid
    +

    Base
    {http://www.visionlearning.com/library/modules/mid58/Image/VLObject-488-021202021211.gif} arrow
    Acid
    +

    Salt
    HCl
    +
    NaHCO3
    {http://www.visionlearning.com/library/modules/mid58/Image/VLObject-488-021202021211.gif} arrow H2CO3
    H2CO3

    +
    NaCl
    (view changes)
    8:45 pm
  7. page Acids and Bases edited ... By: Tana Smithsakol Introduction ... other foods that taste sour over thousands ... the…
    ...
    By: Tana Smithsakol
    Introduction
    ...
    other foods that taste sour over thousands
    ...
    these characteristics:
    Acids taste sour, are corrosive to metals, change litmus (a dye extracted from lichens) red, and become less acidic when mixed with bases.
    Bases feel slippery, change litmus blue, and become less basic when mixed with acids.
    In the late 18th century, Svante Arrhenius, a Swedish scientist proposed that water can dissolve many compounds by separating them into their individual ions. Arrhenius proposed that acids are compounds containing hydrogen that dissolves in water and donates one or more hydrogen ions (H+) into the solution. Acids are known as proton donors.
    An example of the dissociation of hydrochloric acid (HCl) in water:
    || HCl
    H2O
    {http://www.visionlearning.com/library/modules/mid58/Image/VLObject-488-021202021211.gif} arrow H+(aq)
    +
    Cl-(aq)
    Arrhenius proposed that bases are substances that dissolves in water and release hydroxide ions (OH-) into the solution. Bases are also known as proton acceptors.
    An example of the dissociation of sodium hydroxide (NaOH) in water:
    || NaOH
    H2O
    {http://www.visionlearning.com/library/modules/mid58/Image/VLObject-488-021202021211.gif} arrow Na+(aq)
    +
    OH-(aq)
    The Arrhenius definition supports Boyle's observation that acids are bases are the opposites of each other and they counteract each other. The idea that acids can make bases weaker and vice versa, led to a new term called neutralization.
    Neutralization
    Acid and Base Neutralization
    Acids releases H+ ions and bases releases OH- ions into the solution. If acids and bases were mixed together, the H+ and OH- ions would combine to form H2O, or water.
    || H+(aq)
    +
    OH-(aq)
    {http://www.visionlearning.com/library/modules/mid58/Image/VLObject-488-021202021211.gif} arrow H2O
    Neutralization of acid and base will always produce water and salt, shown below:
    *A salt is any ionic compound that contains any combination between the alkaline metals and halogens.
    || Acid
    Base
    Water
    Salt
    HCl
    +
    NaOH
    {http://www.visionlearning.com/library/modules/mid58/Image/VLObject-488-021202021211.gif} arrow H2O
    +
    NaCl
    HBr
    +
    KOH
    {http://www.visionlearning.com/library/modules/mid58/Image/VLObject-488-021202021211.gif} arrow H2O
    +
    KBr
    In 1923, Danish scientist Johnnnes Bronsted and Englishman Thomas Lowry refined Arrhenius's theory. Under the Bronsted definition of bases is any sebstance that can accept a hydrogen ion, and acids are referred to as proton donors because H+ ions are simply protons. And therefore, acids and bases are the opposites. The Bronsted-Lowry definition also explains why some substances that do not contain OH- ions can act like bases which accepts a proton.
    For example, NaHCO3 or baking soda acts like a base by accepting a proton from an acid.
    || Acid
    Base
    Salt
    HCl
    +
    NaHCO3
    {http://www.visionlearning.com/library/modules/mid58/Image/VLObject-488-021202021211.gif} arrow H2CO3
    +
    NaCl
    In this example, the carbonic acid (H2CO3) formed undergoes rapid decomposition into water and gaseous carbon dioxide (CO3 + H2 -> CO2 + H2O), and CO2 gas is released.

    (view changes)
    8:34 pm
  8. page Acids and Bases edited ... By: Tana Smithsakol Introduction ... meaning "sour". In In the seventeent…
    ...
    By: Tana Smithsakol
    Introduction
    ...
    meaning "sour".
    In

    In
    the seventeenth
    ...
    Robert Boyle lit
    For thousands of years people have known that vinegar, lemon juice and many other foods taste sour. However, it was not until a few hundred years ago that it was discovered why these things taste sour - because they are all acids. The term acid, in fact, comes from the Latin term acere, which means "sour". While there are many slightly
    classified different definitions of acids andbases, in this lesson we will introduce the fundamentals of acid/base chemistry.
    In the seventeenth century, the Irish writer and amateur chemist Robert Boyle first labeled
    substances as
    ...
    acids or bases (hebases, he called bases alkalies)alkalies. Boyle labeled these substances according to the followingthese characteristics:
    Acids taste sour, are corrosive to metals, change litmus (a dye extracted from lichens) red, and become less acidic when mixed with bases.
    Bases feel slippery, change litmus blue, and become less basic when mixed with acids.
    (view changes)
    7:56 pm
  9. page Acids and Bases edited Acids and Bases By: Tana Smithsakol Introduction People discovered vinegar, lemon juice and m…

    Acids and Bases
    By: Tana Smithsakol
    Introduction
    People discovered vinegar, lemon juice and many other foods over thousands of years ago. However it was only until a few hundred years ago when people discovered why these foods taste sour. The term acid came from acere, in Latin meaning "sour".
    In the seventeenth century, an amateur Irish chemist Robert Boyle lit
    For thousands of years people have known that vinegar, lemon juice and many other foods taste sour. However, it was not until a few hundred years ago that it was discovered why these things taste sour - because they are all acids. The term acid, in fact, comes from the Latin term acere, which means "sour". While there are many slightly different definitions of acids andbases, in this lesson we will introduce the fundamentals of acid/base chemistry.
    In the seventeenth century, the Irish writer and amateur chemist Robert Boyle first labeled substances as either acids or bases (he called bases alkalies) according to the following characteristics:
    Acids taste sour, are corrosive to metals, change litmus (a dye extracted from lichens) red, and become less acidic when mixed with bases.
    Bases feel slippery, change litmus blue, and become less basic when mixed with acids.

    (view changes)
    7:53 pm

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